Saturday, November 26, 2016

Wet and Warm Thanksgiving Weekend After Large Amounts of High-Elevation Snow

The Thanksgiving has been generally wet and warm, but with large amounts of snow at higher elevations.  The temperatures at Seattle-Tacoma Airport and Stampede Pass (4000 ft) in the Cascades, tells the story (red and blue lines are average highs and lows this time of the year).   Minimum temperatures have been way above normal at both locations.  As I have noted in several blogs, this warmth is due to a persistent area of low pressure off our coast, which has brought in warmth and moisture.

The precipitation over the past day (24h ending 11 AM Saturday) has been impressive over the southern Olympics,  and north Cascades (2-3 inches in places).  You will note a profound rain shadow NE of the Olympics with only .07 inches over northern Whidbey Island (Ebey's Landing is one of my favorite winter walks).



The past seven days has been VERY wet along the coast, with some locations along the slopes of the Olympics and coast coastal mountains getting 10-20 inches)---see left panel below.  The right panel shows the difference from normal for the same period--unusually wet coast.  Some of the coastal river have hit or approached flood stage.

On Thursday and Friday, it was cool enough (and certainly wet enough) that the higher Cascades (above roughly 4000-4500 ft) got hit with several feet of snow (like three feet at Mount Baker ski area).  But it was too warm for the lower ski areas (and particularly Snoqualmie) to get anything on their lower slopes.

And it was made worse last night, when a warm front came through, pushing the snow level up to around 5000 ft.  The time-height cross section above Seattle shows this clearly (red is temperature in C, blue wind barbs, ordinate is pressure (850 is about 5000 ft), and time increases to the left (in UTC)


A weak frontal zone is now draped over the Northwest coast with light to moderate precipitation  (see radar below)
As the day goes on the front will slip eastward with precipitation stopping and the air cooling aloft.

Sunday morning will be a good time for outdoor activities (or to take part in the Seattle marathon) or to get across the passes.   Later Sunday, a strong (but cooler) frontal system will move in and will it should be raining over the lowland by dinner time.

7 comments:

John said...

It's been especially warm east of the Cascades;55 today in Spokane. November temps are running 8-9 degrees above normal;it will be the warmest since at least 1934.

windlover said...

Long range models and the NWS forecast are hinting for more of a cool down towards the end of next weekend...highs near 40, lows near freezing. What's your take on this?

Carter Mountain Chronicals said...

What's this about a cold wave and possible lowland snow headed our way in Western Washington lowlands for the first week of December?

Thecatguy93 said...

Actually Mt. Baker got 48 inches in 48 hours, not three feet. And they have the most snow of any ski area in the US currently. And it's not true that Snoqualmie did not get snow on the lower slopes. Summit West got seven inches at the base, I crossed the pass and saw it myself. Although it has since melted down a bit.

Andy James said...

How many consecutive years of wildly anomalous weather constitute a pattern? 10° F above historical averages is really terrifying, especially when the Arctic is even wackier, and in the context of multiple years setting records. And we don't have the Blob to blame any more, right?

duffinator said...

Cliff,

can you explain why Mount Baker gets so much snow? Is it more moisture flow up north? Or does it have to do with more moisture due to more lift over Mount Baker and Shuksan ridge? Cold air from Frasier River?

thanks

Grant Gunderson said...

Baker does great, but so does Paradise on Rainier as well as Alyeska. However nothing compares to what the areas in Japan get.